In pneumatic and electropneumatic automation, associating distributors in functional blocks, each having a common pressure duct and one or two common exhaust ducts passing therethrough, has become a practice that is widespread, that significantly simplifies implementing distributors, and that leads to installations that are particularly well organized.
For each group of pneumatic actuators in an installation, a functional block is made up that comprises as many distributors as there are actuators to be controlled separately. This functional block is located close to the actuators and requires only one pressure feed and only one or two exhaust returns. In addition, in the more recent versions, the functional block can also receive all of its electrical power supply and commands via a single cable having multiple conductors connected via pluggable sockets.
In practice, the pneumatic actuators disposed in a single installation are of various sizes and they can have very different requirements for compressed air. In principle, each actuator should be associated with a distributor of caliber corresponding to its own size and air flow needs. This is what is generally done, and it is this optimization of caliber that restricts the extent to which a functional block can be made uniform. In a group of pneumatic actuators that are to be associated with a single functional block, the actuators are generally varied, and until now manufacturers have been offering only associations of distributors that are identical in caliber, thereby requiring the distributors for the smaller actuators in the group to be expensively overdimensioned.